Method and apparatus for cracking hydrocarbons



Jan- 12, 1960 E. s. PETTYJOHN ETAL METHOD AND APPARATUS F'OR CRACKING HYDROCARBONS Filed Dec. 5, 1955 QAM ATTORNEYS- 4 FUEL f f f f///f/ /f//f United States Patent() METHOD AND APPARATUS FOR CRACKING HY DROCARBONS Elmore S. Pettyjohn, Evanston, Henry R. Linden, Franklin Park, and Jack M. Reid, Villa Park, Ill., assignors to Institute of Gas Technology, Chicago, Ill., a Acorporation of Illinois Application December 5, 1955, Serial No. 550,874

13 Claims. (Cl. 2604-679) This invention relates to the manufacture of gas rich in unsaturated aliphatic hydrocarbons, particularly acetylene. More specifically, the invention provides an improved apparatus and method for thermally cracking a wide range of lluid hydrocarbon feed stocks with exceptionally high yields of acetylene. Additionally, the invention provides an unusuallyhigh concentration of acetylene in the product gas.

So far as we know, the present invention provides the only practical thermal cracking process for converting to acetylene hydrocarbons having a boiling range up to that of Bunker C oil. Conventionally, the feed stocks are limited to those hydrocarbons more volatile than natural gasoline, such as natural gas, ethane-rich gases, propane,butane and liquefied petroleum gases. In accordance with these prior processes, the light hydrocarbons to be crackedto produce a gas rich in Yunsaturated hydrocarbons is mixed with steam andthe temperature of the steam and the hydrocarbon is brought up to cracking level by passing the mixture through a tube furnace or a refractory vessel filled with hot checker brick. If petroleum oils are substituted for the low molecular weight aliphatic hydrocarbon as the feed stock, increasing quantities of tar and carbon will be formed as the molecular weight and carbon-to-hydrogen weight ratio of the feed stock` are increased. When operating under such conditions, the cracking apparatus may become choked with tar and carbon.

According to one feature of our invention the hydrocarbon feed stock in vapor or highly dispersed form is introduced into a rapidly flowing stream of superheated steam at a temperature above lthe cracking temperature required for the production of the `desired unsaturated aliphatic hydrocarbons. The volume and temperature ofv the superheated steam is calculated to raise the temperature ofthe hydrocarbon` above the minimumtemperaturefor conversion to acetylene, say, 2000 F. A major `proportion of the heatV required for cracking is supplied by the superheated steam. The temperature of thehydrocarbon feed stock is instantaneously raised from room temperature or from 600-900 F., if the stock is preheated, to above 2000 F.y The residence time inthe reactor is a fractionF of 'a second, normally less than 0.1 second. Preferably the reaction is carried out at subatmospheric pressure, say, 0.5 atmosphere, where con'- version to maximum amounts of acetylene is desired. TheV product gas, rich in acetylene and ethylene, is then immediately quenched in cooling liquid to Vstabilize it.

In the production of acetyleneY in accordance with this invention relatively large quantities of ethylene are also produced. If itis desired to favor conversion to ethylene, this may be' conveniently done merely by modifying the cracking temperature andresidence time as hereinafter pointed out.

Another object of the invention is to providev an apparatus for carrying out this process which maybe operated continuously and in which the hydrocarbon feed stock ICC and the superheated steam are homogeneously intermixed within a fraction of a second. Y Y Y l Y Another object is to provide a cyclic regenerative apparatus wherein the steam is superheated by passage through one of a pair of refractory vessels containing hot refractory shapes and is discharged from said Vessel into a reactor interconnecting the two vessels. 1 l n These and other objects and advantages of our invention will be apparent from the following description when read in conjunction with theaccompanying drawings, in which:

Figure l is a semi-diagrammatic vertical section through an apparatus constructed in accordance with the invention;

Figure 2 is a sectional view taken along the line 22 of Figure 1;

Figure 3 is a `sectional view taken along the line 3-3 of Figure l; and

Figure 4 is a view similar to Figure l showing another `form of the invention utilizing a vertical reactor and horizontal regenerators or heat exchangers.

The hydrocarbon feed stocks most useful in this invention include those hydrocarbons having a molecular weight of propane or higher, and include inter alia natural gas liquids, petroleum oils, shale oils and liquid products derived from the carbonization of solid fuels. Natural gas or ethane-rich gas streams may also be used, butvare not as desirable from the economic standpoint. Preferably, the liquid hydrocarbon is preheated and introduced into the reactor in vapor or highly dispersed form. A suitable preheating temperature may range up to 800 or 900 F. The cracking of the hydrocarbon feed stock is carried out in the presence of superheated steam at a temperature ranging from 2000 to 2500 F. or higher and at a residence time in the reactor ranging fromv 0.01 to 0.1 second if maximum acetylene production is desired. It is essential in accordance with the present process that the steam and the hydrocarbon Vbe mixed thoroughly to achieve maximum efficiency. The major source of heat for the cracking reaction is supplied by the atmosphere of superheated steam. The steam is heated to a temperature of, say, 3000 to 4000 F. and the volume ofsteam used is suificient to raise the ternperature of the fluid hydrocarbon introduced into the flowing steam to the desired level. We have found that a minimum of about iive pounds of 3000 F. steam is required for each pound of hydrocarbon at a reaction temperature of 2300 F. The quantity of steam may range to twelve pounds and above. The advantages in using higher proportions of steam in acetylene production are several:

(l) Greater quantities of heat are available permitting attainment of higher temperatures;

(2) The partial pressure in the reactor is lowered;

(3) The residence time within the reactor is shortened; and

(4) The amount of carbon deposited within the reactor is minimized.

We have also found that the proportions' of superheated steam required to provide the minimum reaction temperatures favorthe production of a high proportion of acetylene and ethylene in the product gas. In accordance with this invention, we have produced gases containing as high as 40 volume percent of acetylene plus ethylene and converted natural gas liquid feed stocks to 65 weight percent of acetylene plus ethylene. As indicated, the relative proportions of acetylene and ethylene may be varied by varying the cracking conditions. We have obtained up to 35 weight percent conversion to acetylene in a single pass.

A portion of the process steam can be replaced by recycling the tail gas obtained after recovery of acetylene,

ethylene or any other valuable unsaturated aliphatic hydrocarbons from the product gas by one of the conventional liquid absorption or activated carbon adsorption processes. This tail gas will be rich in hydrogen which results in high heat carrying capacity and a beneficial effect on the extent of conversion of the higher carbon content and higher molecular weight feed hydrocarbons.

By introducing the vaporized or highly dispersed hydrocarbon directly into the superheated steam, the hydrocarbon is brought to reaction temperature instantaneously. In prior processes-the temperature of the hydrocarbon feed stock and the steam depended upon heat transfer through reactor tubes or from the checker brick within a refractory vessel. Obviously,fthisv method of heating the hydrocarbon feed stock requires a much longer time relatively and during this period considerable carbon and tar results from the cracking, especially in the case of the higher molecular weight hydrocarbons.

Immediately upon discharge from the reactor the efuent gases are quenched to stabilize the acetylene and ethylene therein. Preferably, direct water spray is used which reduces the temperature to below 1000 F. Immediate quenchingto instantaneously reduce the temperature of the gas results in higher yields of acetylene and ethylene and justifies the loss of heat which results from the quenching operation. Of course, a portion of the heat in the steam generated and the heat in the cooled efuent gases can be utilized in a waste heat boiler for the generation of steam which is subsequently superheated for use in the reaction, or for preheating the hydrocarbon feed stock, as desired.

Where maximum production of ethylene is desired, the reaction temperature is reduced to as low as 1500 F. and the residence time lengtheneed up to one second, normally about 0.1 second. Generally, the residence time at which optimum ethylene yields are obtained at a given temperature decreases with increasing temperature, but it will be understood that maximum ethylene yields will generally be obtainned in the temperature range between 1500 to 2000 F. when operating in accordance with the invention. While decreases in total and patrial pressure favor ethylene formation, as they do acetylene formation, it is not necessary to maintain `as high steam dilutions or as low total pressures in ethylene production. Steam-to-hydrocarbon ratios may range as low as 2 pounds per pound of hydrocarbon at atmospheric pressure for substantial ethylene conversion.

In the accompanying drawings we have shown several forms of apparatus which are suitable for practicing the process of the invention.

Referring to Figure 1, a pair of vertical heat exchangers or regenerators 2 and 3, identical in construction, are provided with heavy insulated walls 4 made out of ceramic refractory brick or the like and filled with heavy duty refractory shapes 5, such as checker bricks or regenerator tiles, which have a high surface-to-volume ratio. The insulating ceramic materials used in the construction of the regenerators also `should have high heat capacity so that the generator is capable of absorbing and releasing large quantities of heat as required. The refractory shapes -5 are supported by steel` structures 6, 7. 'Ihe chambers 8, 9 beneath the steel support 6 permit uniform distribution of air and steam as these materials are passed upwardly through the regenerators. The top of each regenerator narrows down to form a throat or passageway 11, 12 which connects internally to an interconnecting cylindrical reaction chamber 1 horizontally disposed above the tops of the regenerators and supported thereby. The volume of the two regenerators is preferably at least thirty times the volume of the reactor. The preferred construction of passageways 11 and 12 is best shown in Figure 2, which indicates clearly that these passageways connect tangentially to the cylindrical interior of the reactor 1. The tangential connection permits thorough intermixing of the materials entering the reactor. The passageways 11 and 12 connect near opposite ends of the reactor. The reactor extends at either end a short distance beyond the passageways and terminates in valved discharge conduits 21, 26 adapted to carry away the reaction products. Water lines 22, 27 equipped with valves 23 and 28 connect to the conduits 21 and 26, respectively, to provide quench water for the reaction products flowing therethrough. Preferably, the water lines terminate in a spray head for promoting uniform distribution throughout the reaction products.

For introducing the fluid hydrocarbon feed stock to the reactor, valved conduits 13 and 17 are provided. These connect tangentially to the interior of the reactor 1 at a point diametrically opposite the passageways 11 and 12..

Thus, steam or combustion air which is passed upwardly through the passageways 11 and 12 from the regenerators 2, 3 becomes thoroughly and homogeneously intermixed with the fluid hydrocarbon entering the reactor through the lines V13 and 17. Thus, the spaces in the outer ends of reactor 1 serve as mixing chambers. Branch lines 15 and 19 containing valves 16 and 20 are provided to furnish fuel in fluid form through lines 13 and 17 to the mixing chambers in opposite ends of the reactor. Combustion of the fuel and of any carbon deposited during the cracking step provide heat for the cracking process. Natural gas, residual product gas after removal of desired constituents, natural gas liquids or petroleum oils may be used for fuel. Air for oxidizing the fuel and any deposited carbon is provided through lines 35 and 31 which join the lower chambers 8 and 9 of regenerators 2 and 3. Also connected to chambers 8 and 9 at the lower ends of the regenerators 3 and 2 are outlet conduits which contain -valves 40 and 41 and lead to a stack 39 for discharging products of combustion resulting from burning the fuel. Branch lines 33, 37 connect to chambers 9 and 8 through lines 31 and 35 for supplying steam to the regenerators 3 and 2. The steam may be generated in waste heat boilers (not shown) heated by product gases and vapors.

Preferably, the interior of the cylindrical reactor 1 is provided with the refractory ceramic cylinders 10, as best shown in Figure 3, or other suitable refractory shapes which are adapted to distribute the ow and temperature uniformly throughout the entire space within the reactor.

In operating the apparatus shown in Figures 1-3, it will be understood that preferably all Valves are operated automatically in the proper sequence by means of a suitable timing mechanism (not shown). The first step in the operation is to heat the regenerator 2 by introducing air through the conduit 31 and heat fuel through conduit 15 by opening valves 32 and 16. As the air passes up through the regenerator 3 (which has been heated during a previous cycle), it becomes heated and mixes with fuel introduced through the line 15 into the mixing chamber at the left end of the reactor 1. The fuel may be the same material used for feed to the cracking reaction. Burning of the fuel takes place in the reactor, and the products of combustion pass through the reactor and downwardly through the checkered brick in regenerator 2 to heat the regenerator to the desired temperature. Depending upon the reaction to take place in the reactor, the regenerator will be heated anywhere from 2500 to 4000 F. The products of combustion are discharged through the lower chamber 8 of regenerator 2 and out through the'stack 39 past open valve 41. After the regenerator 2 has been heated to the desired temperature. valve 41, valve 32 in the air supply line 31, and the valve 16 in the fuel supply line 15 are closed. We are now ready to carry out a thermal cracking reaction in reactor 1.

First, the steam valve 38 in line 37 is opened to purge the regenerators, the steam passing upwardly through regenerator 2, across the reactorl, downwardly through the egenerator 3, and out "the Vstack 39 through open valve `40. After afshort `time, the valve 40 to the stack 39 is closed and the hydrocarbon feed stock (preferably preheated), Which is intended to be cracked in the presence of very highly superheated steam flowing upwardly through the regenerator 2, is introduced into the mixing chamber of the reactor by opening'the valve 18 in line 17. The hydrocarbon flows tangentially at high velocity `into the reaction chamber from one side, while the superheated steam ows tangentially at high Velocity into the reactor from the other side through passageway 11. Thus, a turbulent condition prevails which causes the steam and hydrocarbon to become liomogeneously inter- ,mixed. Most ofthe heat Vrequired for the thermal cracking reaction is supplied from the superheated steam. The valve 30 in discharge conduit 26 is opened and the reaction products resulting from cracking the hydrocarbon in the presence of steam within the reactor are discharged continuously through the conduit 26 at the lett end of the reactor. Simultaneously, the valve 28 in water line 27 is opened so that quench water is sprayed into the product gases which are flowing out of the reactor uto the conduit 26, thereby reducing the temperature below the stable level of the desired products. The product gases and steamproduced from the quench water are passed through a waste heat boiler or heat exchanger to recover a portion of their sensible and latent heats and are then conveyed into a suitable separator from which the gaseous products are removed by a suitable gas pump and from which any condensed liquids are removed by a suitable liquid pump. Operation without heat recovery can be accomplished by using a water quench to less than steam condensation temperature.

The cracking reaction is continued until such time as the refractories in regenerator 2 fail to heat the steam to the reaction temperature. At this time the valves 18, 28 and 30 are closed and outlet valve 40 is opened. After a short period suitable to purge the combustible reactants from the apparatus, valve 38 is closed and the air valve 36 and fuel valve 20 are opened to initiate the reverse cycle. The air passes upwardly through the relgenerator 2 and causes the fuel introduced through the line 19 to burn together with any carbon deposited during the thermal cracking step. The products of combustion ow through the reactor 1 and downwardly through the regenerator 3 to heat the regenerator to the desired temperature. The products of combustion pass out through the valve 40 into the stack 39. Valves 36, 20 and 40 are then closed. The valve 41 is opened. Steam is introduced upwardly through the regenerator 3 by opening the valve 34. The steam ows through the reactor 1, downwardly through the regenerator 2 and out through the valve 41 into the stack 39. After a short time, the flow of steam completely purges the set and the valve 41 is closed. At this time the hydrocarbon feed stock is permitted to flow into the reactor where it is mixed, in the manner indicated previously, with the very hot superheated steam flowing upwardly through the passageway 12 from the regenerator 3. The cracking reaction is carried out as the homogeneously intermixed reactants pass through the reactor. The product gases ar'edischarged through the conduit 21 where they are quenched by water flowing into the discharge conduit 21 through the line 22.

It can be seen from the foregoing description that only l steam, air and combustion products are passed through the regenerators. By not passing the reaction products from the thermal cracking reaction through the regenerators, the refractory surfaces remain free from carbon and tar deposition, as normally found in other cyclic thermal cracking processes, which results in very efficient regenerator operation.

Analternative form of the apparatus is shown in Figure 4, In this form the regenerators 50 and 51V are disposed horizontally in end Ato end position with the reactor 60 interposed With its upper end Ybetween the ends of the regenerators. The reactor is mountedvertically. In this form of the invention the ow through `the reactor is all in one-direction-downwardly. The regenerators 50 and 51 are constructed in substantially the same way as the regenerators 2 and 3 shown in Figure l. Of course, necessary modifications are made to compensate for the fact that they are disposed horizontally rather than vertically. Outlets 62 and 63 are provided to carry away the products of combustion land steam to a stack. Conduits 52, 54 and 53, 55 connect to the outer ends of the regenerators for supplying airand steam, respectively, as indicated in Figure 4. The hydrocarbon feed stock is introduced through a single linej57 connecting to the upper end of reactor 60 and the heating fuel is introduced through a side branch 59. A discharge conduit 64 connects to the lower end of the reactor 60 and is equipped with suitable means for quenching the .product gases which ow therethrough consisting of Water line 65.

The steps in the operation of this apparatus are the same as those for the apparatus shown in Figures 1 through 3. In this form of the inventionl only one discharge conduit and one set of feed conduits are connected to the reactor since the flow is all in one direction. Intermixing -of the steam, which passes from the regenerators into the reactor through passages 56 and 61, and the hydrocarbon feedstock is accomplished in an expeditious manner due to the fact that the flow of steam is at right angles to the ow of feed hydrocarbon through the conduit 57. This causes considerable turbulence and results in a homogeneous mixture of the reactants before they advance down the reactor.

Below, three examples are given which illustrate the conversion of a petroleum oil and of two natural gas liquids to acetyleneandrethylene with the apparatus described herein. These examples are based on an apparatus having a reactor volume of 0.184 cubiefeet:

Example I (Favors acetylene production) Feed stock Petroleum oil Operating conditions: f

Process hydrocarbon feed, lb./hr 11.15 Steam feed, lb./hr. of 10 p.s.i.g. steam 83.5 Hydrocarbon used as fuel, lb./hr 7.6 Hydrocarbon feed preheat temperature entering reactor, F 900 Steam superheat temperature entering reactor, F 3000 Reactor temperature, F 2300 Reactor pressure, atm-, 0.5 Residence time in reactor, sec 0.03 Operating results:

Product gas volume, s.c.f./hr 342 Acetylene yield, wt. percent 27.0 Ethylene yield, wt. percent 15.0 Product gas composition, mole percent` Acetylene 12.8 Higher acetylenes 0.7 Ethylene 6.9 Higher olelins and aromatics 1.6 Hydrogen 50.2 Methane 13.6

Ethane 0.1 CO 7.4 CO2 1.5 .N3 5.2

. Example Il (Favors ethylene production) Feed stock-.. Natural gasoline Operating conditions:

1b./hr 13.9

Operating results:

Product gas volume, s.c.f./hr 312 Acetylene yield, wt. percent 7.9 Ethylene yield, wt. percent...v 37.2 Product gas composition, mole percent- Acetylene 5.1 Higher acetylenes 0.8 Ethylene 22.2 Higher olens and aromatics 6.2 Hydrogen 35.0 Methane 20.4 Higher parans 0.7 CO 8.2 CO2 1.4 N2 0.0

Example III (High acetylene and ethylene production) Feed stock Butane Operating conditions:

Process hydrocarbon feed, lb./hr 20.3 Steam feed, lb./hr. of p.s.i.g. steam 99.4 Hydrocarbon used for fuel, lb./hr 8.7 Hydrocarbon feed preheat temperature ening reactor, F 900 Steam superheat temperature entering reactor, F 3000 Reactor temperature, F 2300 Reactor pressure, atm 0.5 Residence time in reactor, sec 0.025 Operating results:

Product gas volume, s.c.f./hr 448 Acetylene yield, wt. percent 25.7 Ethylene yield, wt. percent 40.0 Product gas composition, mole percent- Acetylene 16.9 Higher acetylenes 1.3 Ethylene 24.4 Higher olens and aromatics 1.7 Hydrogen 33.9 Methane 18.7 Ethane 0.2 CO 2.3 CO2 0.3 N2 0.3

Various other modifications will occur to those skilled in the art without departing from the true spirit and scope of'our invention. It is, therefore, our intention not to limit our invention other thanV as necessitated by the scope of the appended claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. A cyclic regenerative apparatus for the cracking of hydrocarbon feed stock which comprises a pair of regenerators capable of absorbing and releasing heat, means for heating said regenerators, a-pair of steam lines connecting to the lower ends of said regenerators, a cylindrical reaction chamber interconnecting the upper ends of said regenerators, a pair of conduits connecting tangentially with the interior of said reactor near opposite ends thereof above each of the regenerators for introducing said hydrocarbon feed stock and mixing said feed stock with steam flowing upwardly from said regenerators, said reactor terminating at either end in a discharge conduit for reaction products, and liquid quenching means associated with said discharge conduit for shock quenching the reaction products.

2. The apparatus of claim 1 wherein said regenerators communicate with said reactor through tangential passageways opposed to the hydrocarbon feed conduits.

3. The apparatus of claim 1 wherein said reaction chamber is packed with refractory shapes of high heat capacity and high surface-to-volume ratio.

4. The apparatus of claim 1 wherein the volume of said pair of regenerators is at least thirty times that of said reactor.

5. A cyclic regenerative apparatus for cracking hydrocarbons which comprises a pair of aligned regenerators horizontally disposed in end to end relation, means for heating said regenerators, an elongated reaction chamber vertically disposed between the ends of said regenerators with its upper end interconnecting with said ends of the regenerators, a steam line connecting to each regenerator at the ends thereof opposite said reaction chamber, a feed conduit connecting to the top of said reaction chamber for introducing said hydrocarbon substantially at right angles to the flow of steam entering the reaction chamber from the regenerators to promote turbulent liow and homogeneous intermixing of the steam and hydrocarbons, a discharge conduit for reaction products at the lower end of said reaction chamber, and liquid-quenching means associated with the discharge conduit for shock quenching the reaction products.

6. A method for making a gas rich in acetylene which comprises preheating a liquid hydrocarbon having a boiling range up to that of Bunker C oil to a temperature of 600-900 F., mixing said preheated hydrocarbon with a rapidly flowing stream of superheated steam to instantaneously raise the temperature of the hydrocarbon to a cracking temperature in excess of 2000 F., thermally cracking the hydrocarbon within a period of less than 0.1 second in the presence of said superheated steam to produce a gas rich in acetylene, the major proportion of heat for said cracking reaction being supplied by said superheated steam, and immediately quenching said gas to cool it below stabilizing temperature.

7. A method for making a gas rich in acetylene and ethylene which comprises mixing a uid hydrocarbon having a boiling range up to that of Bunker C oil and a temperature between room temperature and 900 F. with a rapidly ilowing stream of high-temperature super.- heated steam to instantaneously raise the temperature of the hydrocarbon to a cracking temperature in excess of 2000 F., thermally cracking the hydrocarbon in the presence of said superheated steam to produce a gas rich in acetylene and ethylene, and immediately quenching said gas to cool it below stabilizing temperature.

8. A method for making a gas rich in acetylene which comprises cyclically introducing in vapor form and at a temperature below that Vat which any thermal cracking occurs a fluid hydrocarbon having a boiling range up to that of Bunker C oil into a rapidly owing stream of superheated steam to instantaneously raise the temperature of said hydrocarbon to a cracking temperature above 2000 F., thermally cracking said hydrocarbon within a. period of less than 0.1 second in the presence of said superheated steam to produce a gas rich in acetylene, the major proportion of heat for said cracking reaction being supplied by said superheated steam, and immediately quenching the product gas to cool itbelow 1000 F.

9. A method for making a gas rich in acetylene which comprises mixing a liquid hydrocarbon having a boiling range up to that of Bunker C oil and a temperature be- 'tween room 'temperature and 900 F. with a rapidly llowing stream of superheated steam to instantaneously raise the temperature of the hydrocarbon to a cracking temperature in excess of 2000 F., thermally crackingthe hydrocarbon at subatmospheric pressure within a period of less than 0.1 second in the presence of said superheated steam to produce a gas rich in acetylene, the major proportion of heat for said cracking reaction being supplied by said superheated steam, and immediately quenching said igas to cool it below stabilizing temperature.

10. A method for making a gas rich in ethylene which comprises mixing a uid hydrocarbon having a boiling range up to that of Bunker C oil and a temperature between room temperature and 900 F. with a rapidly owing stream of superheated steam to instantaneously raise the temperature of the hydrocarbon to a cracking temperature in excess of 1500" F., thermally cracking the hydrocarbon within a period of less than 1.0 second in the presence of said superheated steam to produce a gas rich in ethylene, the major proportion of heat for said cracking reaction being supplied by said superheated steam, and immediately quenching said gas to cool it below 1000 F. l

11. A method for making a -gas rich in acetylene which comprises mixing a liquid hydrocarbon having a boiling range up to that of Bunker C oil and a temperature between room temperature and 900 P. with a rapidly owing stream of superheated steam and recycled hydrogen-rich residual product gas to instantaneously raise the temperature of the hydrocarbon to a cracking temperature in excess of 2000 F., thermally cracking the hydrocarbon within a period of less than 0.1 second in the presence of said superheated steam and said recycle gas to produce a gas rich in acetylene, the major proportion of heat for said cracking reaction being supplied by said superheated steam and said recycle gas, immediately quenching said gas to vcool it below stabilizing temperature, and separating said acetylene from said gas, the remainder constituting said residual hydrogen-rich product gas.

12. A method for making a gas rich in ethylene which comprises mixing a liquid hydrocarbon having a boiling range up to that of Bunker C oil and a temperature between room temperature and 900 F. with a rapidly ilowing stream of superheated steam and recycled hydrogen-rich residual product gas to instantaneously raise the temperature of the hydrocarbon to a cracking temperature in excess of 1500 F., thermally cracking the hydrocarbon within a period of less than one second in the presence of said superheated steam and said recycle gas to produce a gas rich in ethylene, the major proportion of heat for said cracking reaction being supplied by said superheated steam and said recycle gas, immediately quenching said gas to cool it below stabilizing temperature, and separating said ethylene from said gas, the remainder constituting said residual hydrogen-rich product gas.

13. A method for making a gas rich in ethylene which comprises preheating a uid hydrocarbon having a boiling range up to that of Bunker C oil to a temperature below that at which any thermal cracking of the hydrocarbon occurs, mixing said preheated hydrocarbon with a rapidly owing stream of superheated steam to instantaneously raise the temperature of the hydrocarbon to a cracking temperature in excess of 1500 F., thermally cracking the hydrocarbon within a period of less than 1.0 second in the presence of said superheated steam to produce a gas rich in ethylene and immediately quenching said gas to cool it below stabilizing temperature.

References Cited,` in the file of this patent UNITED STATES PATENTS 2,422,081 Cottrell June 10, 1947 2,520,149 Keeling Aug. 29, 1950 2,552,277 Hasche May 8, 1951 2,572,664 Robinson Oct. 23, 1951 2,643,936 Pike June 30, 1953 2,750,420 Hepp June 12, 1956 2,813,138 McQueen Nov. 12, 1957 2,816,941 Goins Dec. 17, 1957 2,866,836 Begley et al. Dec. 30, 1958 

1. A CYCLIC REGENERATIVE APPARATUS FOR THE CRACKING OF HYDROCARBON FEED STOCK WHICH COMPRISES A PAIR OF REGENERATORS CAPABLE OF ABSORBING AND RELEASING HEAT, MEANS FOR HEATING SAID REGENERATORS, A PAIR OF STEAM LINES CONNECTING TO THE LOWER ENDS OF SAID REGENERATORS, A CYLINDRICAL REACTION CHAMBER INTERCONNECTING THE UPPER ENDS OF SAID REGENERATORS, A PAIR OF CONDUITS CONNECTING TANGENTIALLY WITH THE INTERIOR OF SAID REACTOR NEAR OPPOSITE ENDS THEREOF ABOVE EACH OF THE REGENERATORS FOR INTRODUCING SAID HYDROCARBON FEED STOCK AND MIXING SAID FEED STOCK WITH STEAM FLOWING UPWARDLY FROM SAID REGENERATORS, SAID REACTOR TERMINATING AT EITHER END IN A DISCHARGE CONDUIT FOR REACTION PRODUCTS, AND LIQUID QUENCHING MEANS ASSOCIATED WITH SAID DISCHARGE CONDUIT FOR SHOCK QUENCHING THE REACTION PRODUCTS.
 6. A METHOD FOR MAKING A GAS RICH IN ACETYLENE WHICH COMPRISES PREHEATING A LIQUID HYDROCARBON HAVING A BOILING RANGE UP TO THEAT OF BUNKER "C" OIL TO A TEMPERATURE OF 600*-900* F., MIXING SAID PREHEATED HYDROCARBON WITH A RAPIDLY FLOWING STREAM OF SUPERHEATED STEAM TO INSTANTANEOUSLY RAISE THE TEMPERATURE OF THE HYDROCARBON TO A CRACKING TEMPERATURE IN EXCESS OF 2000*F., THERMALLY CRACKING THE HYDROCARBON WITHIN A PERIOD OF LESS THAN 0.1 SECOND IN THE PRESENCE OF SAID SUPERHEATED STEAM TO PRODUCE A GAS RICH IN ACETYLENE, THE MAJOR PROPORTION OF HEAT FOR SAID CRACKING REACTION BEING SUPPLIED BY SAID SUPERHEATED STEAM, AND IMMEDIATELY QUENCHING SAID GAS TO COOL IT BELOW STABILIZATING TEMPERATURE. 